688 



HISTORICAL GEOLOGY. 



Dimetrodon of Cope, "vrhicli has several Texas species, remarkable for the 

 great length of the neural spines of the lumbar vertebrae which supported the 

 broad dorsal fin characteristic of the genus ; and other related genera, for 

 which Cope instituted the family of Theromora — made by some a part of 



1125. 



'"^f^ft^ 



Mesosaurus tumldus (natural size); 1-5, tarsals ; I-V, metatarsals. Cope. 



the group Anomodontia. Other related species, from New Mexico, are the 

 OpMacodon grandis Marsh, about 10 feet long ; also species of Sphenacodon 

 and Notliodon of Marsh. These early Ehynchocephalians and Anomodonts 

 combine Amphibian and Mammalian characteristics along with the Reptilian. 



Characteristic Species. 

 1. Carboniferous Period. 



Plants. — 1. Seaweeds are rare in the Coal-measures. A Spirophyton, like S. cauda- 

 galli (page 582), has been reported by Lesquereux as occurring in sandstone, probably of 

 this era, or of the Subcarboniferous, in Crawford County, Ark. Species of the genus 

 Caiclerpites have been observed in Pennsylvania, Illinois, Indiana, Missouri, in both the 

 Lower and Upper Coal-measures. Chondrites CoUetti Lsqx. was obtained near Lodi, Ind., 

 overlying a thin coal-bed at the base of the Coal-measures. Lesquereux remarks that, 

 although the iron-stone concretions have preserved the most delicate parts of Ferns and 

 Insects, no trace of a Fungus or Lichen has been found in them. He observed elsewhere, 

 however, evidences of parasitic Fungi. A large Fungus, having some resemblance to an 

 Agaricus, has been reported, with illustrations, by H. Herzer, from the Lower Kittanning 

 coal-bed of Tuscarawas County, Ohio, and named Dactyloporus archcBus. 



2. Lepidodendrids. — Fig. 1033, part of the surface of the Lepidodendron aculeatum 

 Sternb., a common species both in the United States and in Europe ; 1034, L. clypeatum 

 Lx. ; 1036, L. Veltheimanum St., which is also Subcarboniferous and European ; 1035, 

 Halonia pulchella Lx., Arkansas. Other common species, and of wide range, are Lepi- 

 dodendron Sternbergii (also Subcarboniferous), L. dichotomum Brgt., L. modulatum Lx. 



3. Sigillarids. — Fig. 1037, Sigillaria SillimaniBrgt., Pa., Ind. ; 1038, S. Pittstonana 

 Lx., Pittston, Pa., Ky. 



